SmartStart No Longer Available on S9 Using Face Mask

[Physician]

I've been using the ResMed AutoSet S9 since early July 2010. SmartStart/AutoStart was available, but yesterday the machine displayed that, even in Clinician's mode, StartStart was available only for pillows. Either in Patient Mode or Clinician's Mode the SmartStart could not be activated if "Face Mask" were selected.

You might recall that in prior posts I complained that there's a ten second delay to full minimum pressure using auto-start and a face mask, so it is certain that auto start was available when the face mask setting was used.

Any S9 users having this issue ? Could it be that the machine was mistakingly on "pillow" setting when using a face mask and that's why auto-start/SmartStart was available ? Or is something wrong with my machine ? (I have never read the Clinician's Manual, but I'm hoping you well-read geniuses out there have a quick answer).

Would someone please try the patient and clinician's settings to see what seems to be the problem ?


PARAMS
AutoSet
8-18
Face Mask
Ramp Off
SmartStart (want this on, but it's greyed out)


Thank you.

[jdm2857]

SmartStart is not available when full-face masks are used. With the mask on and the blower off, the anti-asphyxia valve in the mask opens. With the valve open, much of your breath volume enters and exits through the valve, making the machine less able to detect your breathing and automatically turn on. Since this makes SmartStart unreliable, it is disabled when full-face masks are set in the mask option.

[Physician]

SmartStart is not available when full-face masks are used. With the mask on and the blower off, the anti-asphyxia valve in the mask opens. With the valve open, much of your breath volume enters and exits through the valve, making the machine less able to detect your breathing and automatically turn on. Since this makes SmartStart unreliable, it is disabled when full-face masks are set in the mask option.

Thank you.



1. Did you read this or experience this ? Where may I find documentation of this ?

2. Wonder why it worked for a few months ? I did have face mask and SmartStart selected. It did easily detect the initiation of my breathing.

3. What are the consequences of using a face mask and setting the S9 to pillows and SmartStart ?

[derhalli]

1- I noticed that auto detect won't work with face mask. It makes sense due to the valve in the full face mask.
2- Maybe you had the mask type changed by mistake to pillow or nasal. If you allow the patient to change the mask type, then anybody in the house can play with the machine and make such change without you knowing it.
3- APAP machines (and CPAPs in general) have the pressure sensor in the body of the machine. The machine would expect a certain drop of pressure on the other side of the tube based on the mask type. Usually, full face masks has higher leak rate and causes lower pressure. Now, the APAP machine will adjust the pressure drop on the other side of the tube by increasing the pressure on the machine side based on mask type. For example, If you set the pressure to 10 and you are using nasal pillow mask, the machine will blow air with pressure of 11 (will result in 10 at the mask after a drop of 1). If you use a full face mask, the machine will blow air at a pressure of 13 (will result in 10 as the mask is bigger and leaks more). So, if you set mask type as pillows and use a full face mask, you will end with wrong and lower pressure. Also, all reporting of data will be wrong including pressure, leak rate, AHI, ...etc. Apnea detection algorithms are different per mask type too.
Also, the pressure adjustment that the machine does, is not a fixed number/mask type. It is more of a curve that changes value with set pressure. Don't try to simply increase set pressure by 1 or 2 to offset for mask type....

[ozij]

When I switch to a full face mask, my S8 automatically cancels the smart start.
With my FFM on, and blower off, the air I breathe goes in and out of the anti-asphyxia valve.

The S8 (I don't know the details of the S9) uses the mask type to calculate the expected leak. FFM leak more that do pillow masks, and whe I forgot to change the setting from pillows, and used a FFM, the machine reported I leaked a lot - much more than on a normall FFM night.